This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. As the U.S. aging population increases, it is especially important to understand how ethanol affects older people. Aged females are at greater risk for the negative health consequences of ethanol consumption compared to aged males. Hormonal changes specific to aging females could contribute to changes in the effects of ethanol, which include greater sensitivity to certain subjective effects. The proposed research will increase our understanding of the neuropharmacologic effects of ethanol in aged females and the role ovarian hormones. Positive modulation of the effects of the neurotransmitter gamma-aminobutyric acid (GABA) at GABA(A) receptors is a critical component of the pharmacologic effects of ethanol. The proposed studies will determine whether the neuropharmacologic mechanisms mediating ethanol effects 1) differ between young and aged female non-human primates, which have similar ethanol metabolism and reproductive hormone cyclicity as humans, and 2) are altered by surgically-induced menopause. The studies will use an operant procedure, drug discrimination, in which subjects are trained to press one lever after nasogastric administration of ethanol and another after water. Without taste cues, subjects must attend to the subjective or discriminative stimulus effects of ethanol. A food treat is delivered only after presses to the correct lever. After training, the subjects will be tested for sensitivity to the discriminative stimulus effects of ethanol and the substitution of three progesterone derivatives produced by the ovaries that positively modulate GABA(A) receptors. These data will provide information about the role of ovarian hormones in age-related changes in sensitivity to ethanol and its neuropharmacologic mechanisms.